Gapless neutral fermions in insulating YbIr<sub>3</sub>Si<sub>7 </sub>revealed by specific heat and thermal conductivity
ORAL
Abstract
Kondo insulators have been intensively re-investigated recently due to non-trivial topology [1], unconventional quantum oscillations (QOs) [2], and evidence for existence of itinerant charge-neutral fermions (CNFs) [3]. Although it has been proposed the CNFs may produce the QO signals, the origin of the CNFs is highly elusive and under debate.
YbIr3Si7 is a newly discovered Kondo lattice compound, where c-f interaction leads to insulating ground state with antiferromagnetic (AF) ordering [4]. The AF ordering can be easily tuned by an external magnetic field. Here we present specific heat C and thermal conductivity κ measurements of YbIr3Si7. Between 2 and 3 T, where the AF order is suppressed, C is strongly enhanced and a finite residual linear term in the thermal conductivity κ/T (T → 0) is observed. A likely possible explanation for the present results is that CNFs are coupled directly to the spin degrees of freedom of the underlying Kondo lattice. YbIr3Si7 thus provides an intriguing platform to study the CNFs and their relationship with magnetism in strongly correlated insulators.
[1] M. Dzero et al., Annu. Rev. Con. Mat. Phys. 7, 249 (2016).
[2] Z. Xiang et al., Science 362, 65 (2018).
[3] Y. Sato et al., Nature Physics 15, 954 (2019).
[4] M. Stavinoha et al., arXiv:1908.11336v2.
YbIr3Si7 is a newly discovered Kondo lattice compound, where c-f interaction leads to insulating ground state with antiferromagnetic (AF) ordering [4]. The AF ordering can be easily tuned by an external magnetic field. Here we present specific heat C and thermal conductivity κ measurements of YbIr3Si7. Between 2 and 3 T, where the AF order is suppressed, C is strongly enhanced and a finite residual linear term in the thermal conductivity κ/T (T → 0) is observed. A likely possible explanation for the present results is that CNFs are coupled directly to the spin degrees of freedom of the underlying Kondo lattice. YbIr3Si7 thus provides an intriguing platform to study the CNFs and their relationship with magnetism in strongly correlated insulators.
[1] M. Dzero et al., Annu. Rev. Con. Mat. Phys. 7, 249 (2016).
[2] Z. Xiang et al., Science 362, 65 (2018).
[3] Y. Sato et al., Nature Physics 15, 954 (2019).
[4] M. Stavinoha et al., arXiv:1908.11336v2.
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Presenters
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Yuki Sato
- Kyoto Univ
- Physics, Kyoto University
- Department of physics, Kyoto University